1. Field of the Invention
The present invention relates to a semiconductor light emitting apparatus having a light detecting device for detecting emitted light, particularly to a semiconductor light emitting apparatus favorably applicable to uses where a high degree of light detection accuracy is demanded.
2. Description of the Related Art
Hitherto, a semiconductor light emitting apparatus for such uses as optical fiber and optical disk has been provided with a light detecting mechanism for detecting the light emitted from a semiconductor light emitting device incorporated therein, as means for making constant the light output level of the semiconductor light emitting device. The light detecting mechanism can be composed, for example, of a reflector for branching a part of the emitted light, and a semiconductor light detector for detecting the emitted light thus branched. In such a configuration, however, the number of component parts would be large, and it would be necessary to lay out the reflector and the semiconductor light detector at a high accuracy in relation to the semiconductor light emitting device. As a measure to solve such a problem, a configuration may be contemplated in which the semiconductor light emitting device and the semiconductor light detector are formed integrally.
However, where the semiconductor light emitting device and the semiconductor light detector are formed integrally, the semiconductor light detector may detect not only the stimulatedly emitted light to be intrinsically detected but also spontaneously emitted light. In such a case, therefore, the light output level of the semiconductor light emitting device which is measured on the basis of the light detected by the semiconductor light detector includes an error corresponding to the spontaneously emitted light. Accordingly, the semiconductor light emitting apparatus with such a configuration is not suited to uses where high-accuracy control of light output level is demanded.
In view of the foregoing, Japanese Patent No. 2877785 (hereinafter referred to as Patent Document 1) proposes a technology in which a control layer is provided in a semiconductor light detector so that a part of spontaneously emitted light inputted from a semiconductor light emitting device is shielded before being detected by the semiconductor light detector.